16. Is there a limit on the amount a donor can contribute to a political party during an election?

p. 37 of  the GRECO report on political party and campaign finance. GRECO (2008) Evaluation Report on the Slovak Republic, Transparency of Political Party Funding (Theme II). https://rm.coe.int/CoERMPublicCommonSearchServices/DisplayDCTMContent?documentId=09000016806ca464

There are no explicit quantitative restrictions on the amount (value) of the donations and free of
charge services a political party (in the electoral campaign) may receive, but candidates may nevertheless not spend more than certain ceilings.